IsDBNull not working in class when in App_Code folder

Question

User1935984934 posted

I am cleaning up my code and found out that some codes are not running when the class is moved into the App_Code folder.  

For example IsDBNull .. Chrw ... and  IsNothing all statements are working fine when the class is outside the App_Code folder See print screen below

Answer 1

User475983607 posted

You're missing references. 

System.Data.SqlClient

https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader.isdbnull(v=vs.110).aspx

Click on the help icon to the left of the error for assistance.

Answer 2

User1120430333 posted

Most likely, there is no import statement  for the  Microsoft.VisualBasic namespace in the class or classes when it/they are moved to the App_Code folder. As opposed to when the classes are not in App_Code folder, Microsoft.VisualBasic namespace is known by your solution if the import for namespace Microsoft.VisualBasic is not present in the class or classes.

https://msdn.microsoft.com/en-us/library/microsoft.visualbasic.information.isdbnull%28v=vs.110%29.aspx?f=255&MSPPError=-2147217396

What's the purpose of you trying to use the App-Code folder anyway? Are you trying to come up with some kind of VB.NET module like coding thing? 

Answer 3

User1935984934 posted

What's the purpose of you trying to use the App-Code folder anyway? Are you trying to come up with some kind of VB.NET module like coding thing?

No, I just thought that the App_Code folder should be used to store no form related elements. 

Answer 4

User36583972 posted

Hi Corobori,

In a Web site project, you can store source code in the App_Code folder, and it will be automatically compiled at run time. The resulting assembly is accessible to any other code in the Web application. The App_Code folder therefore works much like the Bin folder, except that you can store source code in it instead of compiled code. The App_Code folder and its special status in an ASP.NET Web application makes it possible to create custom classes and other source-code-only files and use them in your Web application without having to compile them independently.

You can refer the following articles.

A Beginner's Guide to ASP.NET Application Folders
https://www.codeproject.com/Articles/31557/A-Beginner-s-Guide-to-ASP-NET-Application-Folders

App_Code folder doesn’t work with Web Application Projects (WAPs):
http://vishaljoshi.blogspot.com/2009/07/appcode-folder-doesnt-work-with-web.html

Best Regards,

Yong Lu